Useful tool to keep tabs on an iffy network connection.

nettest.sh

#!/bin/bash
# Licensed under any of GPLv2, MIT, and BSD 2-clause licenses

TEST_ADDR='4.2.2.1'
INTERVAL=10
VERSION='nettest v0.2a, keith beckman'

args=$(getopt vhi:H:V $*)

function usage () {
  cat <<EOF
Usage: nettest [-H host_addr][-i seconds][-hv][-V]

nettest pings a host (default 4.2.2.1) at intervals (default 10s) and reports
if the network is down. If -V (verbose mode) is enabled, it will print a dot
every time it successfully pings.
EOF
	exit 2
}

if [ $? != 0 ]; then
	usage
fi

set -- $args

for i; do
	case "$i" in
		-H)
			TEST_ADDR="$2"
			shift;;
		-i) 
			INTERVAL=$2
			shift;;
		-v)
			echo $VERSION
			exit 2;;
		-V)
			VERBOSE=1;;
		-h)
			usage;;
	esac
	shift
done


function isUp() {
	ping -Q -c 1 "$TEST_ADDR" > /dev/null  2>&1
	return $?
}

while true; do
	if isUp; then
		if [[ $VERBOSE ]]; then
			printf "."
		fi
	else
		printf "\nERROR: (%s) Network down\n" "`date`"
	fi
	
	sleep "$INTERVAL"
done